Intro to Immunology Flashcards
What are the two types of immunity?
Innate and Adaptive
Where are immune responses generate? (three places)
Primary Lymphoid Organs
Secondary Lymphoid Organs
Sites of infection
What is an antigen?
Any substance that causes your immune system to produce antibodies against it.
- May be a foreign substance from the environment, such as chemicals, bacteria, viruses, or pollen.
- May be formed inside the body, as with bacterial toxins or tissue cells
How are antigens recognized?
Toll-Like Receptors
Antigen Receptors
What is the physiological function of the immune system?
Defense against infectious microbes
Who theorized and discovered the first example of manipulating the immune system? Which disease was studied?
Edward Jenner
Smallpox (related to Cowpox)
What is cross-reactivity?
A reaction between an antigen and an antibody that was generated against a different but similar antigen
Which disease is the only one to be completely eradicated from nature?
smallpox
What is innate immunity?
A response involving non-antigen-specific barrier defenses.
-Similar response to virus, fungi, bacteria, etc.
What is adaptive immunity?
Antigen specific response. Only reacts when there is a specific protein present.
Which phase of the immune response occurs first?
Innate
-occurs within first hours
(adaptive may not play a role until days later)
What are some physical barriers to infection within the innate response?
Epithelial and Mucosal Surfaces
-block, remove, trap, flush
What are some chemical barriers to infection within the innate response?
Fatty Acids (sweat) Lysozyme and Phospholipase (cell wall breakdown) Low pH (halt growth) Defensins (antimicrobial activity) Surfactants (antigen clearing)
What is the main biological barrier to infection within the innate response?
Normal flora (prevent colonization)
- release toxic substances
- out-compete for attachment
All leukocytes are derived from _________ stem cells in _____ _________.
Hematopoietic
Bone marrow
What are myeloid cells? List the three classes.
Leukocytes derived from a myeloid progenitor cell
- Granulocytes
- Monocytes
- Dendritic Cells
Name the granulocytes.
Basophils
Eosinophils
Neutrophils
What do monocytes (in circulation) differentiate into (in tissue)?
Macrophages
What are Lymphoid cells? List the types.
Leukocytes derived from lymphoid progenitor cells
- Natural Killer Cells
- T Cells
- B Cells
Which lymphoid cells are innate and which are adaptive?
Natural Killer = innate immune cells
T Cells/B Cells = Adaptive immune cells
Why are natural killer cells an exception?
They are lymphoid cells but participate in innate immunity
Myeloid Cells are derived from ______ _____ ______.
Myeloid Progenitor Cells
Lymphoid Cells are derived from ______ ______ _____.
Lymphoid Progenitor Cells
Describe Neutrophils.
Granulocytes PHAGOCYTIC Large Cells (and abundant) FIRST RESPONDERS Multi-lobed nucleus Produce chemotactic agents for other leukocytes
Describe Basophils.
Granulocytes Least abundant (0.2%) Triggered response due to IgE Release inflammatory mediators Pathological role in ALLERGY
To which leukocyte are mast cells similar?
Similar to Basophils
However, they are found in tissues NOT blood
Describe Eosinophils.
Granulocytes
Bi-Lobed nucleus (Neutro = multi-lobed)
Functions in IgE mediated degranulation and eradication
Numbers rise during allergic reactions
2-5% of leukocytes (N>L>M>E>B)
Eradicate LARGE, extra-cellular parasites
Natural Killer cells will attack cells that are lacking ____.
MHC
What do natural killers cells target?
Virally infected cells
Tumor cells
(cells with decreased MHC = indicate infection)
What are the second cells to response to “trouble”?
Monocytes(blood)/Macrophages(tissue)
Which leukocyte is important in antigen presentation and clearance of dead cells/debris?
Monocytes/Macrophages
contain an arsenal of lysozymes and antibiotic proteins
Which cells are important in linking innate to adaptive immunity?
Dendritic Cells
Where are dendritic cells typically found?
Skin, mucosa, lymph nodes, spleen, thymus
-MINOR population in the blood-
Dendritic cells express ________ molecules.
MHC II
Which cell type is important for internalizing/processing Ag, presenting Ag peptides to T Cells, and activating T Cells?
Dendritic Cells
Which branch of the immune response is most effective?
Adaptive
Lymphocytes are extremely important for ________ immunity.
Adaptive
- immunologic specificity
- immune regulation
- immune memory (vaccinations)
Lymphocytes produce _______ agents to attract other leukocytes and produce ________ agents to activate or deactivate other leukocytes.
Chemotactic
Cytokines
Adaptive immunity is comprised of both a ________arm and a __________ arm.
Humoral
Cell-Mediated
Why are both arms of adaptive immunity needed?
-They use different mechanisms to attack pathogens
-Effective against different microbes
(they work cooperatively)
Humoral immunity is primarily effective against ________ _________.
Extracellular Microbes
Cell-mediated immunity is primarily effective against _________ _________.
Intracellular Pathogens
How do we tell immune cells apart?
Cluster of Differentiation (CD) Markers
What is the CD for T cells?
CD3+
What is the CD for Helper T Cells?
CD3+ and CD4+ = CD4+ T Cells
What is the CD for Cytotoxic T Cells?
CD3+ and CD8+ = CD8+ T Cells
What are the three types of antigens?
Immunogen
Tolerogen
Allergen
What is an immunogen?
an antigen that elicits an immune response
What is a tolerogen?
an antigen that induces immunological tolerance or immune non-responsiveness
What is an allergen?
an antigen that causes an immediate hypersensitivity reaction (allergic reaction)
What are endogenous antigens?
Antigens generated within the cells of the body as a result of normal metabolism or viral infection
-Presented by APCs to CD8+ T Cells
What are exogenous antigens?
Antigens directly entering the body from the environment
- inhaled (pollen), ingested (food), injected (splinter or vaccine)
- Presented by APCs to CD4+ T Cells
Endogenous Antigens are presented by APCs to ______ T Cells whereas Exogenous are presented to ______ T Cells.
CD8+
CD4+
______ immunity develops at the site of infection, whereas ______ immunity develops in regional lymph nodes.
Innate
Adaptive
Describe the steps of Lymphocyte Activation.
- Microbe infects host
- Microbe is taken up by APC at site of infection
- APC enters lymph circulation and into LN
- Naiive T and B Cells enter Lymph Nodes
T Cells and B Cells are found in specific zones of a lymph node:
Lymphoid Follicle =
Parafollicular Cortex =
B Cell Zone
T Cell Zone
Activation of naive lymphocytes (within lymph node) leads to clonal expansion and differentiation into ________ and ________ lymphocytes.
Effector
Memory
After differentiation, effector and memory lymphocytes will enter circulation in order to reach __________.
The site of infection (in peripheral tissue)
What is the difference between memory and effector lymphocytes within peripheral tissues?
- Effector T Cells (and antibodies) = enter tissue and eliminate antigens
- Memory Lymphocytes = Take up residence in tissue AND secondary lymphoid organs in preparation for the next infection
What are the basic steps in adaptive immunity?
- Antigen Recognition
- Lymphocyte Activation (differentiation)
- Antigen Elimination (humoral or cell-mediated)
- Apoptosis (homeostasis)
- Memory
What happens to immune cells if no antigen is being presented?
T Cells will leave the lymphoid organ and re-enter circulation
What are the two physiochemical variables that control leukocyte entry into peripheral sites?
Blood Flow (shear force) Electrostatic Interactions
Shear force (blood flow) controls leukocyte entry into peripheral tissue. Do pre- or post- capillary venules have less shear force and thin vessel walls?
POST- capillary venules = less shear force
How do electrostatic interactions control leukocyte entry in peripheral sites?
- There is a net negative charge on endothelia and inflammatory cells under physiological conditions (natural repulsion)
- Injury/infection = change in charge distribution leads to electrostatic grasping
What are the two methods for controlling leukocyte entry into peripheral sites?
Physiochemical Variables
Cellular Adhesion Molecules for lymphocyte homing
Peripheral lymph nodes and Peyer’s Patches have _______ endothelial venules.
Thick
Which homing receptor is used by lymph nodes to retain naive T lymphocytes?
L-Selectin
binds to “L-selectin Ligand” on endothelial cell
Which homing receptors are used for adhesion of activated T lymphocytes (memory and effector) at the site of infection?
E-Selectin Ligand (binds E-selectin on endothelial cell)
P- Selectin Ligand (binds P-selectin on endothelial cell)
The receptor-ligand pair function as the initial weak adhesion to the cytokine activated endothelium
The homing receptor for Naive T Cells is __________, whereas the homing receptor for Effector and Memory T Cells are __________ and ___________.
L-selectin
E-selectin LIGAND
P-selectin LIGAND
Integrins and Selectin Ligands are attached to the _______ which will “roll” until it finds the matching _____ and ________.
Integrin Ligands and Selectin
What do chemokines do?
Activate integrins
Recruit cells to the site of infection
Once a leukocyte forms stable receptor-ligand pairs with the endothelial cells it will ______ .
Migrate through the endothelium
What are scavenger receptors?
A group of receptors that widely recognize and uptake macromolecules having a negative charge as well as modified LDL (unique to microbes)
What are N-formyl-mehtionyl receptors?
Receptors that bind N-formyl peptides produced by the degradation of either bacterial or host cells. Hence formyl peptide receptors are involved in mediating immune cell response to infection
Name three important receptors on innate immune cells.
N-formyl-methionyl receptor
Mannose receptor
Scavenger receptor
How do cells of the innate immune response detect antigen?
Extracellular Surface TLRs
Intracellular Endosomal TLRs
Toll-like receptors are also known as ______.
Pattern Recognition Receptors
What is the function of TLRs?
They recognize molecules (PAMPs) that are broadly shared by pathogens but distinguishable from host molecules.
What are PAMPs?
Molecules associated with groups of pathogens, that are recognized by cells of the innate immune system
What is the immune consequence of TLR recognition of a PAMP?
- Recruitment of adapter proteins
- Recruitment and Activation of protein kinases
- Activation of transcription factors
- Gene transcription
- Expression of inflammatory cytokines, chemokines, endothelial adhesion molecules, costimulatory molecules, and antiviral cytokines
The TLR signaling cascade involves _______, ______, and ________.
Adaptor Proteins
Protein Kinases
Transcription Factor
Cells of the adaptive immune response are _______ specific.
Antigen
How do cells of the adaptive immune response recognize antigens?
T Cell Receptors (TCR) bind to the antigen and MHC*
*MHC I or MHC II
Which MHC molecule is recognized by CD4+ T Cells?
MHC II
Which MHC moles is recognized by CD8+ T Cells?
MHC I
Accessory receptors of the adaptive immune response are important for ________.
Signal Transduction
What are the three important Accessory Receptors involved in the adaptive immune response?
NFAT
NF-kB
AP-1
